Changes

Jump to navigation Jump to search
1,794 bytes added ,  21:53, 18 May 2010
Created page with 'thumb|right|150px|Deer tick - Scott Bauer ===Hard ticks=== *Hard, chitinous covering over dorsal surface called the '''scutum''' **Unique to hard ticks *…'
[[Image:Deer tick.jpg|thumb|right|150px|Deer tick - Scott Bauer]]
===Hard ticks===

*Hard, chitinous covering over dorsal surface called the '''scutum'''
**Unique to hard ticks
**Males have a scutum which covers the entire body surface
**Females have a scutum which only covers a small area behind the head

*Prominent biting mouthparts

*Festoons ('pie crust edging') around the posterior body margins

*Enamel coloured patches on scutum are present on '''ornate ticks'''

*Female hard ticks may swell up to 3 times their normal size when taking a blood meal

===Soft ticks===

*No scutum

*Mouthparts are not visible from dorsal surface

*Feed little and often as cannot swell as much as hard ticks

==Mouthparts==

*Sensory organs for locating a feeding site called '''palps'''

*Chelicerae for puncturing the skin

*The '''hypostome''' pushes through the wound made by the chelicerae where backwards pointing teeth lock the mouthparts into the skin
**Dorsal groove in the hypostome permits the flow of tick saliva and host blood

==Feeding==
[[Image:Engorged Ixodes scapularis.jpg|thumb|right|150px|Engorged ''Ixodes scapularis'' - Thomas Hedden]]
*Ticks stand upright

*Chelicerae cut through skin creating a pool of blood

*Hypostome is inserted deep into the skin

*Mouthparts are cemented into place

*Ticks feed continuously

*Tick saliva flows into host and contains
**Histamine blocking agents to minimise the host inflammatory response
**Anticoagulants to ensure the free flow of blood
**Cytolysins to enlarge the feeding lesion
**Vasoactive mediators, enterases and carbohydrate splitting enzymes to increase the vascular permeability, facilitating feeding
**Paralytic toxins

*Host tissue is broken down leaving a zone of necrosis creating a '''feeding lesion'''[[Category:Ticks]]
Author, Donkey, Bureaucrats, Administrators
53,803

edits

Navigation menu